Between 13 and 16% of children born in the United States are born prematurely, with nearly 2% of these weighing less than 1500 g (less than three-quarters of a pound). In this latter group, neurological deficits are observed in nearly 90% of those who survive: cerebral palsy is found in 5-10% and deficits in cognition, behavior, or attention is found in about 50%. In 2005, medical costs during the first year of life averaged $41,610, compared to $2830 for a full term baby, for total annual hospital charges of $7.4 billion. Magnetic resonance imaging is being used increasingly to look at the brains of these babies in order to understand why so many have these developmental abnormalities. Most studies have focused upon injury to the white matter of the cerebral hemispheres, but recent studies have discovered frequent abnormalities of development of the cerebellum, a more posterior part of the brain. The cerebellum has traditionally been associated with motor tone and coordination, and more recently has been implicated in cognitive function. As a result, a component of the adverse outcome from prematurity may relate to abnormal cerebellar development. This study proposes to use state-of-the-art magnetic resonance techniques to assess the metabolism and microstructure of the cerebellum during development in prematurely born neonates and to correlate that development with potentially treatable conditions in other organ systems of the baby and with two common conditions of the brain in prematurely born neonates: hemorrhage into the cerebral ventricles, and injury of the cerebral white matter. It is postulated that hemorrhage into the ventricular system and subarachnoid spaces around the cerebellum prevents the cerebellum from receiving important signals from the tissues that cover it, while injury to the cerebral white matter might interfere with signals sent to the cerebellum, thus contributing to cerebellar injury of the premature brain. Identification of the causative factors might allow those factors to be avoided or treated more aggressively, ultimately resulting in less cerebellar damage and improved clinical outcome. PUBLIC HEALTH RELEVANCE: Brain injuries in prematurely born babies enormously increase the costs of health care during the first year of life. In addition, the poor neurodevelopmental outcome that results in poor school performance, and behavioral performance that results in decreased productivity of affected patients after childhood. This study aims to identify causes and, in that way, reduce the incidence of these injuries.